1. Field of the Invention
This invention relates to a weld assembled tank for storage of a liquid such as heavy oil, petroleum, etc. and a method for fastening a shell plate through a supporting members to a base plate in a such weld assembled tank.
2. Description of the Prior Art
In the conventional construction of a storage tank of the type referred to the above, arched shell plates are erected directly on the base plate and the lower end of the former is welded to the latter with fillet weld applied to both the inner and outer surfaces of the joints. However, with a liquid stored in the tank, when a deformation of the tank takes place with a part of or the whole of the tank base coming to subside or the shell plates coming to buldge, a tensile force is imposed on the fillet welded part at the lower end of the inner circumference of the tank in the direction of opening the fillet welded part. Then, this tends to cause cracks in such a part which is loaded with the tensile force or peel off the welded part and then the stored liquid begins to leak. Such leakage tends to lead to very serious trouble.
Since such leakage is dangerous also in terms of environmental pollution or public nuisance, there has been an urgent demand for an improvement over the conventionally employed method of joining shell plates on to base plate of such storage tanks.